This Primary Arms basic scope mount works with M4, AR-15, and similar "flat-top" 1913 Picatinny mounting platforms. Fits scopes with 30mm tubes, or use the included metal 1-inch adapter shims to mount a 1-inch tube scope. Aluminum construction, durable matte black anodized finish. This tough scope mount features a lifetime warranty.Features30mm rings with 1" spacers Picatinny style mountMatte black finish